Tissue biopsy through endoscope or laparoscope requires delivery of a biopsy instrument into a target area, acquiring a sample of tissue by cutting motion of the instrument and retrieval of said sample through said endoscope or laparoscope. The instruments are shaped in general as forward biting and cutting biopsy forceps at distal end, which are connected to a proximal knob via flexible wires. Since size of available biopsy forceps is small and each biopsy sample has to be retrieved separately one at a time, biopsy by endoscopic or laparoscopic forceps requires significant time and increases sampling error.
To circumvent these issues, there have been several devices proposed to collect multiple samples in one insertion of the biopsy forceps without the need to retrieve the forceps each time the sample was obtained.
The U.S. Pat. Nos. 5,746,216 and 6,019,758 describe methods of a multiple sample bioptome by axially linear movement of an outer tube over cutting jaws. Issues of said device include no actual mechanism of transport of procured samples to a sample storage space; narrower diameter of the sample storage space than that of the cutting jaws in closed position, thereby impeding transfer of the procured sample into the storage space.
The U.S. Pat. No. 5,762,069 uses a wire spiral axially located inside a flexible tube of biopsy forceps, which can be rotated to proximally move tissue samples inside the tube as a means for obtaining multiple samples. One drawback of the device is that rotational torque of the spiral needs to be significant enough to transfer samples that are viscous and tend to adhere to inner wall of the device. Another problem is that rotation of the spiral should be axially centered in the tube, which is hard to achieve with only one end of the spiral attached to a proximal end of the device.
The U.S. Pat. No. 5,779,648 proposes dual action mechanism of one of cutting members with rotary motion to cut tissue samples followed by axial motion to transfer said sample into a proximally located sample storage space. Issues of the device include slippery bite of tissue sample for cutting by the cutting unit due to premature transition of rotary biting force to axial motion before completion of cutting; limited axial motion of the cutting unit not adequate enough to push back said samples into the sample storage space; no mechanism to retrieve procured samples from the storage space.
The U.S. Pat. No. 5,782,747 proposes methods of procuring multiple tissue samples by using spring jaws to cut samples from tissue. One major problem is that the proposed mechanism requires tearing-off of tissue for procuring sample without cutting action of the jaws, which in practice would hardly achieve samples of adequate size for assessment. Furthermore the device does not have means to retrieve procured samples.
The U.S. Pat. Nos. 6,053,877, 6,110,127 and 6,632,182 describe methods of obtaining tissue samples serially into an axially longitudinal sample tube located proximally to cutting jaws that are slidably connected to a mid part of a multi-layered biopsy tube. Cutting action to procure tissue samples is achieved by axially linear movement of said layer of the tube. Said tissue samples are then sequentially to be stored by stuffing action of a new tissue sample upon the previously procured and stored samples. Issues of the devices include proximal transmission of distally forward force to move the mid layer upon contact with a target tissue, which may buckle the proximal portion of flexible wire of the biopsy instrument instead of exerting distally forward movement, resulting in inadequate cutting actions; presence of sticky friction between inner wall of the tube and the tissue samples, generating resistance to stuffing action of the newly procured sample; a need to maintain axially straight tubular structure of the tissue sample storage for a certain length to transmit distally forward force for cutting action and to allow proximally linear movement of the samples by backward stuffing action. The U.S. Pat. No. 6,632,182 proposes use of suction to pull in procured samples. Quality of the samples may deteriorate since the samples must travel inside the entire length of the tube upon suction from the distal end of said device to a storage space.
The U.S. Pat. Nos. 6,071,248 and 6,322,522 describe methods of procuring multiple tissue samples by using suction of air or fluid in cavity from which said samples are to be taken. Issues of the inventions include inadequate cutting force of the cutting jaws; adherence of said samples to the cutting jaws resulting in incomplete detachment of the samples from the cutting jaws; inadequate and uncertain mechanism of suction/aspiration to serially stock samples into the sample storage space, with the first stored sample blocking off the suction/aspiration conduit thereby prohibiting further storage of additional samples.
The U.S. Pat. No. 6,083,150 illustrates methods of procuring multiple biopsy samples by installing a sample storage space open to a proximal end of jaws. One drawback of the device is that there is no actual mechanism to proximally transport the samples from the jaws to the storage space other than serially stacking up samples proximally into an opening to the storage space.
The U.S. Pat. No. 6,139,508 uses sequential collections of tissue samples that are to be stored proximally through a sample guide arm. Axially linear transfer of samples to a proximal end is either unassisted or assisted by an auger inside a tube located at a distal end. One method of collecting multiple samples by the proposed device requires adequate forward pressure of the sample guide arm against tissue, which is supposed to proximally push back previously obtained samples stacked in the sample tube. The other method using the auger requires axial rotation of said auger to retrieve samples. Practical problems related to these methods include the forward pressure applied to the sample guide arm pushing the target tissue away from the cutting jaws due to elastic nature of the tissue and lack of adequate transport mechanism of procured samples proximally along the axis inside the sample tube. Furthermore, there is no firm stationary hold on the sample skewered in the auger when said auger rotates. Consequently the sample skewered in the auger may rotate together with the auger and may never move proximally in the sample tube.
The U.S. Pat. Nos. 5,562,102, 5,823,971, 5,840,044, 6,142,957 and 6,419,640 use a skewer in the middle of cutting jaws, which is to pierce a target tissue and pull the tissue into said cutting jaws for cutting. The cut tissue sample then is proximally stacked up along the skewer by subsequently obtained samples. Issues of these devices include poor quality of the samples that are pierced in the middle; inability to retrieve the samples unless the skewer is either completely pulled out from a distal end of the device or the samples are cut off further damaging the quality of the samples; a potential risk of perforation of thin wall of the gut. The U.S. Pat. No. 5,823,971 also proposes use of a cutting sling to cut samples off as an example of procuring samples. Problem of this proposal is that the sling should be both flexible and sharp enough to pull in and cut off samples. This requirement may result in premature material breakage of the sling.
The U.S. Pat. Nos. 5,810,744, 5,961,534 and 6,530,891 describe methods of procuring multiple samples by side cutting action. Issues of these devices include a need to position a distal end of said devices in parallel with a target tissue while maintaining the distal end linearly straight for a certain length to effect cutting actions. The U.S. Pat. No. 5,810,744 has no actual transport mechanism for procured samples to a proximal area of a storage space. The U.S. Pat. No. 5,961,534 proposes use of a wire sling as indexer that can be moved back and forth in front of the procured samples and use of index points that radially extend from an inner wall of said device, which is to capture said samples in the storage space. One issue of the index points is difficulties in manufacturing said points as part of the inner wall. The U.S. Pat. No. 6,530,891 may not have adequate cutting torque of the helical cutting blade since rotational torque must travel a long distance from the proximal end of said device to the distal end.
The U.S. Pat. No. 7,278,971 proposes use of a rack-pinion device located at a distal end of biopsy forceps, for transporting serial samples into storage space. One critical issue is that circular movement of the rack-pinion device located at right angle to the linear axis of said biopsy forceps significantly reduces size of the samples that could be practically transported.
The U.S. Pat. No. 7,794,409 uses a multi-chambered cutting device removably attached to a distal end of endoscope for cutting off and suctioning up tissue samples via a channel in the endoscope to store the samples. One caveat of the device is a need to establish and to maintain negative pressure in the cutting device, which requires tight fitting between the device and the target area. It potentially increases chances of bleeding from the target tissue into a space between the tissue and the device. Another issue is damage to samples during transit along a certain length of the channel of the endoscope.
The U.S. Pat. No. 7,846,107 describes methods of collecting multiple samples into a sample storage space connected to an endoscopic instrument. Samples are to be obtained by conventional biopsy forceps, which then are to be transported through a channel in a tubular shaft of the endoscope by vacuum suction. Said methods require unobstructed transport of the samples in the channel upon vacuum suction through the length of the tubular shaft of the endoscope. One issue of the patent is that vacuum suction may damage samples adversely in a way accurate pathologic interpretations of the samples may be affected.
These aforementioned patents proposed devices and methods, which are limited with inadequate or damageable samples, or with complicated mechanistic actions. Consequently there practically has not been a widespread use of these devices for multiple sampling of tissue. Successful devices and methods require procured samples of good quality and of adequate size for pathologic evaluation; easy operability with conventional endoscopic instruments; consistent operation with minimal variation of operability and of quality of samples upon a range of varied target tissues.